Chronic use of cannabinoids have been reported to affect endocrine secretions and to alter the membranes of erythrocytes, liposomes and mitochondria. These or other toxic manifestations of cannabinoids will be examined to determine if 11-palmitoyloxy-delta-9-THC also shows adverse effects on these parameters. The in vitro rat microsomal drug-fatty acid conjugating system has now been perfected and it will be used to determine if other drugs can be conjugated to fatty acids as is the delta-9-THC metabolite 11-OH-delta-9-THC. Extensive in vitro and in vivo studies will be performed to determine the structural conformation required of a drug in order for it to be conjugated to free fatty acids under in vivo conditions.